The present invention relates to doughnut frying machines and, more particularly, to a flight conveyor for advancing dough forms through a doughnut fryer.
Doughnut frying machines include an elongated tank or frying kettle containing a hot oil or frying shortening bath. A depositor is positioned at one end of the tank. A receiving conveyor adjacent the depositor includes a plurality of equally spaced flights or pusher bars which receive raw dough forms deposited into the tank. The conveyor advances the forms toward a turnover device. The turnover device receives partially fried dough forms, turns them over and delivers them to a delivery conveyor. The delivery conveyor receives the partially fried, turned over dough forms and advances them to a discharge end of the tank. The depositor, the conveyors and the turnover device are synchronized through a chain, drive motor and sprocket arrangement. An example of a doughnut frying machine may be found in U.S. Pat. No. 3,329,081 entitled DOUGHNUT MACHINE WITH FLOATING KETTLE HAVING HEAT TRANSFER COILS AND A REMOVABLE OPERATING UNIT WITH THE KETTLE which issued on July 4, 1967 to Roth.
Generally, each flight conveyor includes a pair of spaced, parallel, endless chains which extend over sprockets along each side of the tank. A plurality of flights or pusher bars extend between the chains in equally spaced, parallel relationship. Adjacent flights define a row area for receipt of a plurality of dough forms. The dough forms are deposited in a row and advanced through contact with the rear most flight. The spacing or pitch between adjacent flights or pusher bars is set for a particular size or limited range of dough forms and, hence, doughnuts. If the size of the dough form is reduced below a predetermined minimum, shingling or collection of the dough forms adjacent one end of the fryer occurs. When the misaligned doughnuts reach the turning device, problems are encountered. The doughnuts may end up stacked on top of each other when transferred through the turning device to the delivery conveyor. The dough forms may be flipped by the turning device back towards the receiving conveyor and then flipped by the turning device to the delivery conveyor so that the same side of the dough form is fried twice. This failure to properly turn or flip the dough forms results in white caps and improperly fried doughnuts.
Heretofore, attempts have been made to minimize or prevent the occurrence of stacking or white caps. One such proposal employs a plurality of air manifolds and nozzles which direct air jets onto the bath in an attempt to keep the dough forms properly positioned in a single row and prevent collection adjacent one side thereof. The use of air jets has generally not been successful, especially when a standard doughnut fryer is used to fry miniature dough forms. Another approach is disclosed in U.S. Pat. No. 4,370,921 entitled DOUGHNUT FRYER GUIDE which issued on Feb. 1, 1983 to Moller et al. As disclosed therein, a fryer guide, including a plurality of elongated, transversely spaced guide bars, is selectively positionable onto or adjacent the conveyor flights. The guide bars may be retracted so as not to interfere with large dough forms as they advance through the fryer. When moved to an operative position, the dough forms are retained in rows by the guide bars which prevent collection of the dough forms adjacent one side of the fryer.
Prior approaches have not been fully satisfactory. Operational difficulties have been encountered. The prior devices have not been readily incorporated in existing machines. A need exists, therefor, for a doughnut fryer flight conveyor which is readily adaptable to the frying of different sized dough forms or doughnuts.